Method and apparatus for establishing electrical contact to a plurality of wires



March 4, 1958 R. ZAPHIROPOULOS ETAL 2,825,836

METHOD AND APPARATUS FOR ESTABLISHING ELECTRICAL CONTACT TO A PLURALITYOF WIRES Filed July 11,. 1955 IN VEN TOR5 establishing electrical tendedto improve upon ways and separable sets 'of conductors on grids nearthetarget area of color employed near the target area,

deposited on a target.

when impacted and excited .light.

.trum, within certain fromeach other. arenecessary.

of one-half each such or reference member.

Unite METHOD AND APPARATUS F913. ETAELISHENQ ELECTRICAL CONTACT T9 APLIJiZALlTY F Application My 11, 1955, Serial No. 521,013 4 Claims. c1.BIB- ie) This invention relates to a method and apparatus for contact toeach of one or more sets The invention is inmeans for making or moreelectrically designed for use television tubes.

in the design and construction of color television tubes wherein one ormore color-control wd focusing grids are it is often desired to have twoelectrically separate sets.

of electrically separable conductors.

electrical connections to each of one grid conductors formed into In thecase of a single gun color television tube employing color switchingnear the target it is customary to employ a grid structure of thisgeneral type to provide so-called color switching and to serve as onecomponent of a series of electron lens elements. In certain types ofsuch tubes, a large number of very narrow phosphor strips are Each ofthese phosphor strips is of a composition which emits a selected colorof light by a scanning electron or cathode-ray beam. In the present art,a tricoloradditive color system is usually used, that is, threediflerentkinds of phosphor strips are deposited on the target, eachadapted to emit a difierent color of light whenimpacted. The threecolors so emitted are chosen so that they may readily becombined andcolor balanced to produce white The three colors chosen will alsoproduce, by

the other colorsof the color speclimitations not material here. 'Incolor television tubes employing grids near a target area variouscombinations for deflecting theelectron beam with respect to target areastrips such as those hereinbefore described, separate sets of gridconductors which are electrically distinct Since the phosphor stripsintheaforementioned types of tubes are arranged in repeating colorcycles of the order of asingle picture (do I .ment in width for eachsuch cycle, and since the grid structure or micro-deflecting means has.a spacing beand deflecting conductors .of the order repeating colorcycle, agreat number of extremely .accurately positioned, tautlyheld andvibration free grid conductors are necessary. Furthermore, since thecolor control switching must be applied during the timethe scanning beamis traversing a lineal distance of the same order of magnitude as thedistance the grid'conductors are spaced apart, the color control tweenthe adjacent .or switching signals are necessarily relatively high infrequency, and in fact he in What is ordinarily termed the radiofrequency or RF range.

The invention herein relates to anovel method and fixture for makingconnection to each of several electrically separable'sets of conductorson agrid designed for use near a target area where the grid conductorshave previouslybeen mechanically secured to the grid frame A numbermaking simultaneousconnections to a large number of suchconductors.For'examplaa low resistanceelectrical contact is desired to eachandevery conductor .in each of problems arise in conductors, ordinarily2,825,836 Patented Mar. 4, 1958 struction of grids such as thosedescribed herein-is that of shielding the connecting and securingstructure. The invention herein results'in a connection to thegrid-wires which is movable andsolves various'problems rela'ting toshielding as will appear" hereinafter.

It is accordingly a principal object of'the invention to provide amethod and fixture "for establishingelectrical contact to a plurality ofwires which will provide relatively low electrical resistance at 'R. -F.frequencies-to each of such wires, which resistance will be uniformforall the wires-contacted and which will not change or vary with age.Another principal object of the invention is to'provide a method andfixture for establishingelectrical contactto each of saidpluralityofwires which is simple, economical, and elficient. Another object oftheinvention is to provide a method and fixturewhich"results in acontacting strip assembly wherein shorts and opens may be easily locatedand cleared.

Another object of the invention is to'provide a means for contacting aplurality of wires incach of several sets of conductorswhich'is'fiexible in relation to the'various design considerationsencountered in assembling a grid adjacent to'the target area ofcolor'television tubes. More specifically in this connection, it isamongtheobjects of the invention'to provide a method andfixturestructure wherein a'connection may be on either end of the grid and tocheer more variously located points on either or both of'such ends, astructure, furthermore, which is movable, both with respect to the gridandfgrid frame and with respect to the other'contacting structures, anda structure which may be easily electron-beamand radiation-shielded,thus avoiding the pick-up of'stray fields or beams which might interferewith'the operation of the grid or grids to which it is connected. It isalso'an object of'the inventionto provide a grid contacting structure ofsuch a form that both the contacting structure and the mechanicalsecuring means may be simultaneously shielded as aforementioned. Anobject of'the invention is to allow simultaneous electrostatic shieldingof the contacting structure and mechanical securing means.

Another principal object of the invention is the provision of a methodand fixture which is adaptable to automatic and semi-automatictechniques of production. A further object of the invention is theprovision of a method and fixture which allows rapid and eificient assembly. Also an object of the invention is the provision of a method andfixture having numerous other objects and advantages, which will becomeapparent to those skilled in the art from the specification herein.

In the invention, electrically separable sets of conductors, which havepreviously been physically secured-in a desired accurate configurationrelative to each other within a grid area proper, as defined by the'gridsupports, are separated into the desired-number 'of'sets of two sets. Inthe 'usual' case,whi ch is that'of grids wherein the 'sets'of gridconductors within the grid area properall lie inoneplane, ornearlywithin one plane, the sets of'gri'd'conductor-s are'separatedadjacent'toeach end of the grid area'into sets of'conductors lying inplanessubstantially parallel to and above I welding operationand thereby makea 3 each other. Temporary means may be employed to hold the physicallyseparated sets of electrically separable conductors distinct from eachother pending further steps of the method. In a preferred method of theinvention, conducting metallic strips of a metal other than thatemployed for the grid conductors are then afiixed to heat conductingpositioning parts of a jig or fixture, that is, to an anvil, to one ormore spacers, and to a clamping piece. In the cases where there are onlytwo sets of conductors to be separated only one spacer is necessary. Theseparated sets of grid conductors are arranged to be included within theconducting strips so mounted on the anvil, spacer and top clamp of thefixture and all the pieces are clamped in position. The anvil, spacer,and top clamp are all composed of a heat conducting material, so as todissipate the heat generated during the desirable electrical andmechanical connection and also to confine the weld to a small section orhead near the edges or' the strips. After the conductors have beenclamped between the strips mounted on the heat conducting parts, awelding means, preferably of the inert gas-shielded type, is run alongthe outermost junction of each of the pairs of strips, thereby joiningthe strips and the conductors in a welded seam, securing the gridconductors bothmechanically and electrically to the joined strips. Dueto the variation in the total thermal conductivity of each the variouscross-sections involved, and the effect of the anvil, spacer and topclamp, in combination with the dissimilar metals being joined, anirregular ball-shaped connection is made at the end of each conductor tothe strips. This connection is so formed that it insures excellentuniform low resistance R. F. electrical contact to each of the gridconductors, and is also trouble-free for very long periods of time. R.F. losses are also at a minimum in this construction. After the weld hasbeen completed, the anvil, spacer, and top clamp may then be removed, aswell as the temporary means, if any, used to'keep the sets of conductorsphysically separated. In the preferred form of the invention, a volatileglue is used to aflix the metallic conducting strips to the anvil,spacer, and top clamp, and the metallic strips are accordinglyautomatically released from the fixture by the welding operation. Thewelding operation also preferably trims the excess of the gridconductors extending beyond the metallic strips automatically.

The invention will be more fully understood, and further objects andadvantages will appear in connection therewith, by the reference to thefollowing description read in connection with the accompanying drawings,wherein:

Fig. 1 is a diagrammatic view, illustrating a preferred form of the ofthe method of the invention, with the end portion of a typical gridframe mounted therein; and

Fig. 2 is a cross-sectional view in elevation of said end portion of theframe, showing the completed grid connection made by the method and inthe fixture of the invention.

Turning now to a consideration of the figures of the drawings, the samenumbers have been used to designate the same parts throughout. In Fig.l, a grid frame 4-9 having a grid support 51 for the fastening of gridconductors 11 by a mechanical means 31, such as a ceramic cement orsilica frit combination, is placed in fixture or jig 10. The form offrame 49 and support 51, as well as the mechanical holding means 31, areof course, only illustrative, and other forms of these components mayprofitably employ the method and fixture of the invention. The-ceramiccement, silica frit combination or other means 31 used to mechanicallysecure the conductors 11 must, of course, be such that the various setsof grid conductors 13, 15 may be electrically isolated from each other.

Fixture is comprised of a bridge assembly 45 partly in cross-section,fixture for the practice sets of grid conductors mounted on base 47 byscrews 43 or other means and having a top or bridging portion 41 lyingin a plane parallel to that of the base 47. Arm 35 is mounted on thebridge 35 by means of pivot 39 and supports top clamp 17. Suitablesecuring means, illustratively the screw 37, serve to secure top clamp17 in position when the fixture it) has been assembled prior to thewelding operation. Also attached to the bridge 45 is an optional shield33 designed to prevent damage to the grid conductors 11 during thewelding operation. Spacer 19 and anvil 21, together with clamp 17, holdthe set of conductors 13 between detachable metallic strips 23 and 25and the set of conductors 15 between detachable metallic strips 27 and29, in position to efiect a weld by welding torch 53. Metallic strips23, 25, 27 and 29 are of a metal other than that employed for the gridconductors 11. Spacer 19 is also preferably of a metal other than strips25 and 27 to avoid any tendency to become welded thereto.

In the application of the method and fixture of the invention, gridframe 49, having electrically separable conductors 11 as describedabove, is mounted in place on jig or fixture 10. The conductors 11 areseparated into the desired sets of conductors 13 and 15 either prior toor after such mounting. Temporary separating means may be employed tohold the sets of conductors 13 and 15 separated until the anvil 21,spacer 19, and top clamp 17 are applied. For example, a narrow glasstape may be placed between the sets of wires 13 and 15 so that thealternate wires forming the one set 15 are below the tape and the restof the wires 13 are above it. The ends of the wires in set 13 and in set15 may then be sandwiched between two sets of masking tape to keep themdistinct and easily separable. Alternatively, the wires may be separatedand immediately placed between the anvil 21, spacer 19 and top clamp 17.A metallic strip 23 is temporarily afilxed to top clamp 17, metallicstrips 25 and 27 are aflixed to spacer19, and metallic strip 29 isafiixed to anvil 21. A glue which is easily volatilized is preferred forthis operation, since such 'a glue will be volatilized during thewelding operation and the strips mounted on clamp 17, spacer 19 andanvil 21 will be released without further efiort. Other means ofsecuring the strips may, of course, be used. Alternatively, strips 23,25, 27 and 29 may be directly applied to the 13 and 15 during theinitial physical separation, in lieu of, for example, the masking tapementioned hereinabove.

Top clamp 17, spacer 19, and anvil 21 are all made of metal or othermaterial with a relatively high coeflicient of thermal conductivity soas to readily conduct the heat involved during the welding operation,thereby performing as chill rings and confining the weld to the edges 1of the metallic strips, and, in addition, helping to create a desirable11. After the. grid conductors in place with each set of conductors 13,15 encompassed respectively between a pair of strips 23-25, and 27-29,screw 37 or its equivalent is operated to clamp the assembly inposition. After the assembly has been so clamped, welding means 53,preferably of the inert gas-shielded type, such as Heliweld or Heliarc,is caused to operate and during such operation to move along adjacent toor in contact wtih the outermost junction of the pairs of strips 23, 25and 27, 29 effecting the welds of each pair of said strips and therespective sets of conductors 13, 15 included therebetween.

It will be noted from the above that the method of the invention may bepracticed by hand, since the anvil 21, spacer 19, and clamp 17 may beprovided with a handle or holding means and the welding torch operatedmanually. During the welding operation, and grid wires 11 are preferablyprotected from damage by a shield 33. The welding operation, in additionto permanently joining the strips 23, 25 with the set of conductors 13,

type of electrical connection to conductors 11 have been clamped andstrips 27, 29 with theset of conductors 15, trims ofi the excess wiresinsets 13and 15.

Ordinarily the sets of grid conductors 13 and 15 will be separated by arelatively small distance, and spacer 19.; will accordingly be oflimited dimensions. For this reason, spacer 19 is preferably of a metalother than that of strips 25 and 27, and preferably such metal has arelatively high thermal capacity, thereby avoiding any tendency tobecome welded to strips 25 and 27 during the welding operation andpermitting ready removal thereafter. Anvil 21 and top clamp 17 mayeasily be made of larger dimension and accordingly may be of the same orof a different metal than strips 23 and 29.

Referring now to the cross-sectional view of Fig. 2 wherein the endportion of the frame 49 is shown in elevation it will be seen toillustrate the appearance of frame 49 after the welding operation hasbeen completed, resulting in connection to conductors 13 by stripassembly 57 and conductors 15 by strip assembly 59. In Fig. 2, frame 49is shown removed from the fixture 10. Support 51 and the mechanicalholding means 31 physically securing grid conductors 11 are illustratedas before. In addition, a combination electron beam and radiation shield55, secured to support 51 by screw 61, is shown. Other forms of shield55 may be employed, and fastened by other means, but it is a specialobject and advantage of the invention herein that the assemblies 57 and59 are movable sufiiciently so that shield 55 may be arranged easily andsimply to cover both the assemblies 57 and 59 and the mechanicalsecuring means 31, forming an effective shield for both.

Attention is especially directed, at novel character of the electricalconnection obtained by the method and fixture of the invention. Aportion of the weld, including the connection, is shown in crosssectionat 57 and at 59 in Fig. 2. It will be noted in Fig. 2 from an inspectionof the contacting strip assemblies 57 and 59 that the ends of theconductor 11, after the weld has been completed, are irregularlyball-shaped in character.

This electrical and mechanical connection is not aifected by themovement of contacting assemblies 57 and 59 to allow the imposition ofshield 55. Shield '55 extends as shown in Fig. 2 to cover both thecontacting assemblies 57 and 59 and the securing means 31. Shield 55thereby functions as a radiation shield and a beam shield, andadditionally as an electrostatic shield. One of the elec trostaticshielding eifects of shield 55 is to keep securing this point, to themeans 31 from charging and discharging and giving undesirable opticaland electrical effects such as electrostatic glows. The shielding asaforementioned of course does not affect the efiiciency of the desirableball-shaped connections to grid conductors 11 in assemblies 57 and 59.

The reason the desired shape and efiicient electrical connection areobtained may be best understood by a consideration of Fig. l. Dissimilarmetals are used for the strips 23, 25, 27 and 29 as compared to the gridconductors 11. As the weld is made, more heat is supplied to the stripsforming the contacting strips 57 than to the grid conductors 11 includedbetween said srips 57 because of the relative amounts of area of eachexposed to the welding means. This heat, however, is confined mainly tothe edges of the strips, due to the cooling or chilling efiectoccasioned by the relatively high thermal conductivity of anvil 21,spacer 19 and top clamp 17. The strips 23, 25, 27 and 29 areaccordingly, during the first instants of the welding operation,rendered more completely in a fluid condition than the ends of the gridconductors 11, and the result is that the ends of grid conductors 11tend to become ball-shaped in character.

This shaping efiect is enhanced by employing a metal having a relativelyhigh thermal conductivity for the strips 23, 25, 27 and 29. Aluminum isthe metal preferred, both for. this reason andbecause of its other.'advantages, such as low electrical resistance and light weight. Infact, contacting strip assemblies 57 and 59 comprised of aluminum strips23, 25 and 27, 29 need no furthersupport than that afforded by theseparated sets of grid conductors 13 and 15. Other metals, such assilver, may also be used for the strips 23, 25, 27 and 29. Gridconductors 11 may be of stainless steel, and the method and fixture ofthe invention has been highly successful with the grid conductors 11composed of this material. However, insofar as the invention herein isconcerned, other materials are also satisfactory for grid conductors 11,and, with most such materials, the additional effects occasioned by therelative thermal conductivities will still obtain if strips 23, 25, 27and 29 of aluminum are employed since aluminum has relatively highthermal conductivity as compared to most metals. Metals other thanaluminum may also be used for the contacting strips 23, 25, 27 and 29,even those of relatively low thermal conductivities, since, as pointedout hereinabove, the desirable electrical connection arises from theeffect of the total heat supplied and the chilling or limiting of thefixture 10, as well as from the effect due to the inherent thermalconductivity of the metals of the strips 23, 25, 27 and 29 and the gridconductors 11.

Arc Welding is the preferred form of welding, although other types ofwelding may be employed, such as resistance welding. Inert gas-shieldedwelding is the preferred form of arc welding. Aluminum, for example, maybe welded without a flux with the inert gas-shielded method. Whenaluminum is welded by this method, an A. C. voltage which has poorregulation and a high open circuit value, or, alternatively, which hassuperimposed high frequency, is desirable for are stabilization. Theshielding gas employed in such a case may be helium or argon, but is notlimited thereto. In a specific application of the method and fixture ofthe invention, helium gas-shielded or Heliarc welding has been found tobe very satisfactory. The particular values employed are 41 volts at 13amperes, for welding aluminum strips to stainless steel grid wires.

The method and fixture of the invention having been described in termsof specific embodiments hereinabove, the invention is to be limited onlyby the following claims.

We claim:

1. In a grid especially adapted to be used near the target area of acolor television tube, a grid contacting assembly for making electricalconnections to at least one electrically separable set of gridconductors which have previously secured in a desired physicalconfiguration by a mechanical supporting means on said grid comprising aplurality of extensions of the grid conductors forming said electricallyseparable set, said extensions protruding beyond said mechanicalsupporting means; a pair of strips of a metal other than the metal ofthe grid conductors arranged oppositely of each other to include saidextensions; and a seam weld joining said pair of strips and said gridconductor extensions at the outermost junction thereof to form saidcontacting assembly.

2. The grid contacting assembly of claim 1 comprising in addition ashielding member arranged to simultaneously cover both said mechanicalsupporting means and said contacting assemblies to provide a shield fromelectron beams and radiation for said mechanical securing means and saidcontacting assemblies.

3. The grid contacting assembly of claim 1 wherein said grid conductorsare stainless steel and said strips are aluminum.

4. A grid construction especially adapted to be used near the targetarea of color television tubes comprising: a frame member including asupport member; a plurality of grid wires; means including said supportmember to mechanically secure said grid wires in a desired configurationrelative to said frame member; extensions of said -gri wires'p'rdtruding: beyond saidsupPOrtniexhbeighmoh- -tacting strip :assemblycomprisinga pairof stripsuof a -rne'te1lother than that of said'gridwires'arranged translyersely of and on either side of saidextensions,'said strips -.and;said wiresbeing joinedin a.-unitary weldedmass at i'the; outermost edges of said strips; a shielding member:.disposed to shield said contacting strip'assembly, grid wireEextensionsand mechanical securing :means; and connectingjmeans forestablishing electrical contact to said contacting strip assembly.

UNI TED sTATEsPATEiiis Law ce

